A material implanted into living tissues should be non-toxic and, after the desired function has been achieved, degraded by metabolic activities and cleared out of the body. Recently, implantation of specific substances into the skin tissue for cosmetic purposes is increasing rapidly. Hyaluronic acid, which is commonly used for this purpose, is known to be metabolized and cleared out of the body within a few days after insertion or implantation regardless of the concentration or the type of the composition. To maintain the desired cosmetic effect for a long period of time, it is necessary to overcome the short period of metabolism of hyaluronic acid in the human body. Therefore, needs on the development of a new filler material that can be maintained for months or longer are increasing.